The present invention relates to capacitive accelerometers, and, more specifically, to accelerometers tolerant of extreme conditions, particularly of high temperatures.
Accelerometers are used to measure acceleration and come in several forms. Capacitive accelerometers have a conductive mass, called a seismic or inertial proof mass, suspended on a spring of some sort between two conductive plates. A gas, such as air or a non-reactive gas, occupies the space between the mass and the plates. The arrangement forms two capacitors, one between each plate and the proof mass with the gas acting as a dielectric. When the device experiences an acceleration, the proof mass moves closer to one plate or the other, reducing the gap between the proof mass and one plate while increasing the distance between the proof mass and the other plate, changing the capacitance in the capacitors. By comparing the capacitances, the direction and magnitude of the acceleration can be determined. However, most capacitive accelerometers can only measure acceleration along one axis because of their structure. To measure acceleration along more than one axis, one accelerometer must be provided for each axis of interest, which can become complicated. In addition, because of their materials and construction, capacitive accelerometers tend to be susceptible to failure at high temperatures, such as might be experienced in a gas turbine.